With 2013 about to come to a close, it's time to take a look ahead to 2014 — and the story lines that promise to dominate the realm of politics.

The health-care debate promises to be front and center once again. (Michael McCloskey/iStockphoto)

Every year there are surprises that seize the spotlight — revelations this year about the National Security Agency's sweeping surveillance, for example — and 2014 probably won't be any exception. But in many ways, the battle lines are drawn for the midterm election year. So without further ado, here are the five biggest things to watch:

1. What's next on Obamacare? Ask the Democrats and Republicans running in swing states and congressional districts next year what weighs on their minds the most, and Obamacare is a very good bet to top the list. Even as the Obama administration has solved many of the technical glitches that plagued the law's implementation this year, a lot of questions remain unanswered. Will enough people enroll in plans though the exchanges? Will new issues pop up? The biggest question for Republicans is: What is the next move? One option is to rally around a palatable alternative. But that would carry the risk of backlash. Another option is to get out of the way and let the law's lousy image take down Democrats who support it. But if the law grows more popular, that's not going to be a great option. Of course, Democrats also face some very tough decisions of their own. We've already seen many incumbents who represent swing states and districts distance themselves from the law and the president. How far will they go if Obamacare's popularity declines even more and the president's image doesn't recover? And will it even be possible to focus on local issues if Obamacare receives as much attention as its gotten this year? These are the questions that could dictate the outcome of the midterm elections.

2. Can Republicans win back the Senate? Speaking of the midterms, the big battle worth watching is the one for the upper chamber. Republicans need to pick up six seats to win back the majority, which leaves them little margin for error, even on a map ripe with opportunity. The disastrous rollout of Obamacare has given the GOP an opening. It damaged the president's image and diminished the standing of vulnerable senators from red states, where the battle for the majority will be won or lost. Democrats' odds of winning back the House majority were never good. And the Obamacare problems have only made them worse. Because of that, the focus of party strategists and groups is likely to center heavily on the Senate.

3. Does anything happen on immigration? This was a big question headed into 2013 following Republicans' lousy showing among Hispanic voters in 2012 and a widespread call in the party to do something about that beginning with reforming the nation's immigration laws. The Senate passed a sweeping measure that has gone nowhere in the House. But that doesn't mean narrower bills can't pass. President Obama mentioned immigration as a 2014 priority during his year-end news conference, so the White House hasn't given up the fight. Neither have Republican reform advocates, as Obama noted. And House Speaker John Boehner's hiring of a well-known immigration policy analyst who has worked for Republicans who have supported allowing undocumented immigrants to earn U.S. citizenship raised hopes among reform activists that GOP leadership still wants to get something done. The question is what can get done and whether any sort path to legalization for illegal immigrants — the touchiest of all the issues in the larger immigration debate — is in the cards. But this much is clear: Unlike the gun debate, which doesn't seem poised for a serious restart in Congress next year, immigration is far from settled, despite stalling in 2013.

4. Return of the debt ceiling. Washington experienced a rare period of fiscal bipartisanship toward the end of the year with the passage of a budget plan that looks to avert the threat of a government shutdown in the near future. But what it didn't do is address the nation's debt ceiling, which the Treasury says can be extended only through late February or early March. Obama is reprising his longstanding refusal to negotiate over the debt ceiling and wants Congress to pass a clean increase. But Republicans, including Rep. Paul Ryan (R-Wis.), who helped author the bipartisan budget plan, aren't going to roll over. They are going to huddle early next year to figure out their asks. What it all means is another showdown without a clear endgame in sight.

5. A extra-special election in Florida. While the 2013 special House elections said little about the national landscape since they unfolded on heavily partisan terrain, in 2014, a hotly contested race in a swing district will unfold early in he year. It promises to be a closely watched campaign which could yield larger messaging and strategy clues headed toward November. We're talking about the race for late-Rep. C.W. Bill Young's Gulf Coast district. The long-serving Republican was so popular that he would have been safe despite the fact the district went for Obama in 2012. But the open race has set off a scramble — and a ton of questions. Can Republicans pin Obamacare's problems to likely Democratic nominee Alex Sink, who isn't weighed down by congressional baggage? Can Democrats find a formula for turning out voters and fighting back against health-care related broadsides? We'll find out in a January primary and March special general election.

Sean Sullivan has covered national politics for The Washington Post since 2012.

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